Many thanks! 
It's a lot of work to set up, but it's been a nice learning experience. Much, much different than configuring a Hi-Fi or guitar amp.
The
key is the quality of the mics and the
proper use of various sound panels. You have to record with as minimal amount of background noise as possible. Those darn mics will pick up EVERYTHING. Even the sound of a car passing by outside.
I usually record about 3-4 takes to choose the best one.
Two AKG C414 mics in front of sound panels, about 12-18 inches from each L300 front grille.
Mics are mixed on a Behringer Q102 mixer. Then fed into the built-in MP4 software in my Sony A7. Flat EQ. I do have two DIY JBL 136A (15-inch) powered subs.
I transfer the sound file to my computer. I usually reduce the files to 720p to speed up the upload time to YouTube.
Video of a recording with an onboard-camera Saramonic mixer.